IMO the NPX300 brings some very important improvements on the table, however I can also understand why some people might not be a fan of it.
This PSU adds more depth, better soundstage, lower noise floor, better precision overall. It does make you understand that the NC200 was engineered to worked with it from the very beginning, so I would consider the NPX300 a must.
At the same time some people might not look for those qualities and might not have speakers (or a setup) that show them in the first place. So a test is mandatory in the first place. Only your ears can decide whether it’s worth the expense of not.
Personally I would also consider better interconnects between the 222 and 250, I suspect (and many confirmed) that they hold back the performance of the system significantly.